EXTERNAL FACTORS ON THL SPAWN DATE 



129 



were lower than any suicc the beginning of February. The 1 3 th to 

 17th March 1929 also saw the spawning quite uninterrupted by the 

 cold spell. The middle of the 1927 season was marked by a slowly 

 falling temperature with no apparent effect on the course of spawning. 

 Turning now to Figs. 33 and 34, we have confu-mation trom two other 

 areas. Probably because of the presence of meteorological staff in the 

 town or village, observers joined the scheme in two places where there 



RAIN 



z ©c mm 



55 25 24 



< prn 



a 



1931 FEB 6 II 16 21 26 3 8 13 18 23 28 2 7 

 YEAR-DAY 42 47 52 57 62 67 72 77 82 87 92 97 



Fig. 32. The Chart for 193 1 



A normal year for rainfall, but interesting because of the very'cold weather 

 early in March. Some spawning took place in this bitter weather, but there 

 was perhaps an accumulation of reports in the exceptionally warm weather 

 that followed. The temperatures are," of course, shade temperatures. A 

 temperature of 19° on the 21st March suggests that some spawn in the sun 

 was near a dangerous temperature. 



were ist Order Observatories, Eskdalemuir, a small village liigh in the 

 hills of southern Scotland, and Valentia in the south-west of Ireland. 

 Fig. 33 shows the weather of the week before spawning in three years 

 at Eskdalemuir {a), {h) and {c), and one at Valentia, {d), and Fig. 34 

 shows the weather at every hour of the day and night at Eskdalemuir 

 in two contrasting years. It is impossible, after looking at these dia- 

 grams, to beheve in any marked connexion between the temperature 

 on the night of spawning and the event itself, for the temperatures 



